Headphone Amp to Pi and Dac + Pro

[museguy]

Hi All,
I am setting up a Raspberry Pi with a HiFiBerry Dac + Pro, running Volumio for desktop headphone use.

Headphones:
Sennheiser HD650
Sony MDR-7506
Denon D2000
Fostex t50rp

So far I have found this ebay headphone amp:
Push-pull mini class A audio stereo Headphone amplifier $151 Shipped

Welcome any suggestions for a $150 Headphone Amp.

Thank you !